You will be given a definition of a task first, then some input of the task.
In this task, you're given a question, a context passage, and four options which are terms from the passage. After reading a passage, you will get a brief understanding of the terms. Your job is to determine by searching and reading further information of which term you can answer the question. Indicate your choice as 'a', 'b', 'c', or 'd'. If you think more than one option is plausible, choose the more probable option to help you answer the question.

Question: What are the symptoms of Castleman's disease? Passage:Herpesviruses are a third group of common cancer-causing viruses. Two types of herpesviruses have been associated with cancer: the Epstein–Barr virus (EBV) and human herpesvirus 8 (HHV-8). EBV appears to cause all nonkeratinizing nasopharyngeal carcinomas and some cases of lymphoma, including Burkitt's lymphoma—the association is especially strong in Africa—and Hodgkin's disease. EBV has also been found in a variety of other types of cancer cells, although its role in causing these other cancers is not well established. KSHV/HHV-8 causes all cases of Kaposi's sarcoma, and has been found in some cases of a cancer-related condition called Castleman's disease. Studies involving other kinds of cancer, particularly prostate cancer, have been inconsistent. Both of these herpesviruses are commonly found in cancerous cells of primary effusion lymphoma. Herpesviruses also cause cancer in animals, especially leukemias and lymphomas.
 Links: a. Epstein–Barr virus b. Epstein–Barr virus c. Primary effusion lymphoma d. Castleman disease
Output:
d